Peter> Per device dirty throttling patches These patches aim to Peter> improve balance_dirty_pages() and directly address three Peter> issues:
Peter> 1) inter device starvation Peter> 2) stacked device deadlocks Peter> 3) inter process starvation Peter> 1 and 2 are a direct result from removing the global dirty Peter> limit and using per device dirty limits. By giving each device Peter> its own dirty limit is will no longer starve another device, Peter> and the cyclic dependancy on the dirty limit is broken. Ye haa! This should be a big improvement. Peter> In order to efficiently distribute the dirty limit across the Peter> independant devices a floating proportion is used, this will Peter> allocate a share of the total limit proportional to the Peter> device's recent activity. I'm not sure I like or agree with this. Shouldn't we be limiting based on the device's capability to sustain traffic? So if I have a RAID device which can read/write a total of 100Mb/sec, while at the same time I've got a CF device which can do 5Mb/sec, shouldn't we be more strongly limiting the CF device, even if it is the only device being written to? Of course, I haven't read the patches yet, nor am I qualified to comment on them in any meanginful way I think. Hopefully I'm just missing something key here in the explanation. Peter> 3 is done by also scaling the dirty limit proportional to the Peter> current task's recent dirty rate. Do you mean task or device here? I'm just wondering how well this works with a bunch of devices with wildly varying speeds. John - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
